/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.graph;

/**
 * These bitmasks are used by edge-flipping algorithms to mark the edge order relative to the
 * original edge direction.
 */
public enum EdgeOrder {

    // bitmasks from triadic census
    FORWARD(0b10),
    REVERSE(0b01),
    MUTUAL(0b11);

    private final byte bitmask;

    EdgeOrder(int bitmask) {
        this.bitmask = (byte) bitmask;
    }

    /**
     * Returns a bitmask used for marking whether an edge is in the same direction as in the
     * original edge set (FORWARD), is flipped relative to the original edge set (REVERSE), or both
     * (MUTUAL).
     *
     * @return edge order bitmask
     */
    public byte getBitmask() {
        return bitmask;
    }
}
